The precise role of kinins in blood pressure regulation, circulatory homeostasis and renal function is unknown. The Brown Norway Rat (BNR) / Catholic strain lacks the substrates for kinin generation, i.e., high and low molecular weight kininogen (HMWK and LMWK) and could serve as an excellent model for studies of the physiology and pathophysiology of kinins. The Catholic strain has not been completely characterized regarding the different components of the kallikrein-kinin system. We have found that the urinary and plasma glandular kallikrein levels are not different in the Catholic strain from normal BNR. Also the urinary kinin levels are normal during salt restricted conditions. This may be related to the activation of a third kininogen (T-kininogen) which is present in rats, also in both strains of the BNR. The enzyme responsible for the physiological activation of T-kininogen is unknown as is the metabolic fate of the generated T-kinin, which we are now investigating. The acute response of the kinin system to inflammatory stimuli in the BNA/Catholic strain is under investigation.